Project Summary/Abstract The Zika virus (ZIKV) is an emerging arbovirus that is spreading rapidly in Latin America. During the onset of the continuing outbreak in Brazil, ZIKV was implicated in the rise in microcephaly, because of the sharp increase in cases of women being infected with ZIKV during pregnancy and having babies and stillborn with severe brain malformation. It has been postulated that in urban areas the yellow fever mosquito, Aedes aegypti, transmits the virus. However, recent studies have suggested that both Ae. aegypti and Ae. albopictus are poorly competent vectors of ZIKV transmission. Additionally, we have demonstrated that when the southern house mosquito, Culex quinquefasciatus, which has high population densities in Brazil and the US, was fed blood spiked with ZIKV in the laboratory, the virus crossed the mosquito?s mid-gut barrier and replicated significantly in the salivary glands. This project seeks to (1) determine unambiguously on the basis of vector capacity whether the southern house mosquito is a vector of ZIKV in Brazil and could transmit the virus in the US; (2) conduct surveillance at the epicenter of the ZIKV epidemic, and (3) investigate whether homemade, natural, and synthetic repellents are effective in fending off ZIKV- infected mosquitoes. Aim #1 will address vector capacity by infecting laboratory and field- collected mosquitoes with a strain of the ZIKV currently circulating in Recife, Brazil, and, subsequently, determine virus replication and titer in the midgut and salivary glands. Additionally, we will investigate whether the virus is transmitted to mosquito offspring. In Aim #2, we will conduct surveillance at the epicenter of the ZIKV epidemic in Brazil to determine whether natural populations of Culex mosquitoes carry the virus. In Aim #3, we will compare the degree of repellence elicited in ZIKV-infected and noninfected Culex mosquitoes by homemade, natural, and synthetic repellents. The proposed work will provide relevant information to guide policy makers and abatement district personnel in their preparedness to prevent a possible Zika epidemic in the US and an endemic crisis in Brazil. Information will also be provided to the public at large about the use of repellents as a prophylactic tool to combat Zika transmission.